The present invention relates to novel benzofuran derivatives. The present invention also relates to inhibitors of steroid 17xcex1-hydroxylase and/or steroid C17-20 lyase and pharmaceutical composition containing the novel benzofuran derivatives.
In the formation of sex steroids in living bodies, 1)C21-steroids, such as a progesterone, are formed from cholesterol, 2)androgenic hormones, such as androstenedione and testosterone, which are C19-steroids, are synthesized from C21-steroids by steroid 17xcex1-hydroxylase and/or steroid C17-20 lyase, and 3)estrogens, such as estrone and estradiol, which are C18-steroids, are synthesized from these C19-steroids as a substrate by aromatase enzymes. All these sex steroids are known to exhibit various activities.
If the steroid 17xcex1-hydroxylase and/or steroid C 17-20 lyase or aromatase, which are enzymes synthesizing these sex steroids, are inhibited, in vivo formation of androgenic hormones and/or estrogens can be controlled. Thus, it is possible to prevent or treat various diseases, in which androgenic hormones or estrogens are involved as an exacerbation factor, such as prostate cancer, prostatic hypertrophy (prostatism), androgenic syndrome (masculinism), andromorphous baldness, breast cancer, mastopathy, uterine cancer, endometriosis, and ovarian cancer.
It is already revealed from numerous findings that these diseases relating to androgenic hormones, such as prostate cancer and prostatic hypertrophy, can be treated by reducing the amount of androgenic hormones in the blood. For example, conventionally decrease in the androgenic hormones was brought about by orchidectomy or adrenalectomy. A decrease in the androgenic hormones originating from the gonad gland by the administration of an LH-RH agonist, which is a kind of hypophysis hormone has been reported recently to exhibit treatment effects.
However, the above-mentioned evisceration is not only psychologically difficult to accept, but also may be accompanied by side effects caused by a decrease of mineral corticoid or glucocorticoid from the adrenal glands. The administration of an LH-RH agonist only inhibits synthesis of hormones of gonad gland origin and is not expected to decrease hormones originating from other organs such as the adrenal glands. In addition, a problem of xe2x80x9cflare phenomenonxe2x80x9d due to a temporary increase of hormones unique to the agonist has been indicated.
On the other hand, although anti-androgenic hormone agents antagonistic to androgenic hormone receptors have been developed, a recent report indicated a decrease in the effect of such an agent due to denaturing of the androgenic hormone receptors.
In view of this situation, development of a more effective agent for decreasing androgenic hormones is desired. It is possible to decrease greatly androgenic hormones by inhibiting steroid 17xcex1-hydroxylase and/or steroid C17-20 lyase. Therefore, inhibition of these steroids is expected to exhibit high effects in the treatment of various diseases in which the androgenic hormones are involved, such as prostate cancer, prostatic hypertrophy, and masculinization disease. In addition, inhibition of steroid 17xcex1-hydroxylase and/or steroid C17-20 lyase may result in interruption of estrogen synthesis.
Up to the present time, steroid compounds and non-steroid compounds have been known as inhibitors of steroid 17xcex1-hydroxylase and/or steroid C17-20 lyase. Examples include non-steroid compounds such as imidazole derivatives disclosed in Japanese Patent Laid-open Application No. 64-85975 and azole derivatives having a condensed three-ring structure disclosed in WO 95/09157. However, because these compounds are not necessarily satisfactory in their effects, development of compounds exhibiting higher activity has been desired.
In view of the above situation, the inventors of the present invention have carried out extensive studies to discover substances inhibiting steroid 17xcex1-hydroxylase and/or steroid C17-20 lyase. As a result, the inventors have found that a certain compound possessing a benzofuran skeleton exhibits potent inhibitory activity of steroid 17xcex1-hydroxylase and/or steroid C17-20 lyase, as well as aromatase. Therefore, an object of the present invention is to provide novel benzofuran derivatives, which inhibit steroid 17xcex1-hydroxylase and/or steroid C17-20 lyase.
Another object of the present invention is to provide novel steroid 17xcex1-hydroxylase and/or steroid C 17-20 lyase inhibitors and pharmaceutical compositions.
The present invention relates to novel benzofuran derivatives. The compounds of the present invention exhibit potent inhibitory activity of steroid 17xcex1-hydroxylase and/or steroid C17-20 lyase. They also inhibit aromatase. Due to its activity, the compounds of the present invention are useful as preventive and/or therapeutic agents for various diseases, in which androgenic hormones and estrogens are involved, such as prostate cancer, prostatic hypertrophy (prostatism), androgenic syndrome (masculinization), andromorphous baldness, breast cancer, mastopathy, uterine cancer, endometriosis, and ovarian cancer.
Specifically, the present invention provides novel benzofuran derivatives represented by the following formula (I) or salts thereof: 
wherein Py is a 2-, 3-, or 4-pyridyl group and R is a substituted or unsubstituted phenyl group or a substituted or unsubstituted aromatic heterocyclic group.
As examples of the aromatic heterocyclic group in the compound of the present invention, heterocyclic groups containing a nitrogen atom and/or sulfur atom as the heteroatom, such as a pyridyl group or thienyl group can be given.
As the substituent on the phenyl group or aromatic heterocyclic group in the compound of the present invention, a hydroxyl group, lower alkyl group, lower alkyloxy group, halogen atom, carboxyl group, lower alkyloxycarbonyl group, carbamoyl group, amino group, amino group which may be substituted with one or two substituents selected from a lower alkyl group and lower acyl group, nitro group, or cyano group can be given. The lower alkyl group is a linear, branched, or cyclic hydrocarbon group having 1-7 carbon atoms, wherein the hydrocarbon group may be substituted with a halogen atom, hydroxyl group, alkyloxy group, amino group, amino group which may be substituted with one or two substituents selected from a lower alkyl group and lower acyl group, nitro group, or cyano group. The number of the substituents may be 1-3, and two of them in combination may form a lower alkylenedioxy group. Preferable substituents are a hydroxyl group, lower alkyloxy group, halogen atom, amino group, and carboxyl group, and particularly preferable groups are hydroxyl, methoxyl, fluorine atom, amino group, and carboxyl.
The following compounds can be given as specific examples of novel benzofuran derivatives represented by the formula (I) of the present invention:
(1) 3-[6-(4-methoxyphenyl)benzo[b]furan-3-yl]pyridine,
(2) 4-[3-(3-pyridyl)benzo[b]furan-6-yl]phenol,
(3) 3-[6-(4-fluorophenyl)benzo[b]furan-3-yl]pyridine,
(4) 3-[6-(3-fluorophenyl)benzo[b]furan-3-yl]pyridine,
(5) 3-[6-(3-methoxyphenyl)benzo[b]furan-3-yl]pyridine,
(6) 3-[3-(3-pyridyl)benzo[b]furan-6-yl]phenylamine,
(7) 3-[6-(3-pyridyl)benzo[b]furan-3-yl]pyridine,
(8) 3-[6-(1,3-benzodioxole-5-yl)benzo[b]furan-3-yl]pyridine,
(9) 3-(6-phenylbenzo[b]furan-3-yl)pyridine,
(10) 3-[6-(3,4-dimethoxyphenyl)benzo[b]furan-3-yl]pyridine,
(11) 3-[3-(3-pyridyl)benzo[b]furan-6-yl]phenol,
(12) 4-[3-(3-pyridyl)benzo[b]furan-6-yl]- 1,2-benzenediol,
(13) 3-[6-(3-thienyl)benzo[b]furan-3-yl]pyridine.
In addition to the above-mentioned compounds, the derivatives of the present invention include salts formed from these compounds and an acid or a base. As acid addition salts, for example, salts with a mineral acid, such as a hydrochloride, hydrobromide, hydroiodide, sulfate, nitrate, and phosphate, and salts with an organic acid, such as a formate, acetate, propionate, oxalate, malonate, succinate, fumarate, maleate, lactate, malate, citrate, tartrate, carbonate, picrate, methanesulfonate, and glutamate can be given. As salts with a base, for example, inorganic salts, such as a sodium salt, potassium salt, magnesium salt, calcium salt, and aluminium salt; organic salts, such as a lower alkylamine salt and lower alcoholic amine salt; salts with a basic amino acid such as lysine salts, arginine salts, and ornithine salts; ammonium salts; and the like can be given. In addition, the compounds of the present invention may form a hydrate or a solvate with a lower alcohol and the like.
The compounds (I) of the present invention can be prepared according to the process shown by the following reaction formula (1), for example.
In the following schematic reaction formula for the preparation of the compounds of the present invention, each symbol used in the compounds is the same as those previously described. 
The hydroxyl group in hydroxy-3-benzofuranone is protected to prepare compound A. Then, after converting compound A into an enoltriflate, compound B is prepared by a cross-coupling reaction using a pyridyl borane derivative and a transition metal catalyst. The protective group is removed from compound B by a deprotecting reaction to prepare compound C, which is then converted into a triflate, followed by a cross-coupling reaction using various types of aryl boronic acid, aryl boronic acid ester, or borane derivative and a transition metal catalyst, thereby obtaining the objective compound (I). R1 in the above reaction formula means a protective group for the hydroxyl group, and an aryl in the cross-coupling reaction indicates a substituted or unsubstituted phenyl group or a substituted or unsubstituted aromatic heterocyclic group. Py represents a 2-, 3-, or 4-pyridyl group. R represents a substituted or unsubstituted phenyl group or a substituted or unsubstituted aromatic heterocyclic group. As required, a substituent on the phenyl group or aromatic heterocyclic group represented by R is modified to obtain the objective compound. Here, example modifications of the substituent include dealkylation of an alkyl ether, acylation or alkylation of a hydroxyl group or amino group, and the like.
In an alternative method of obtaining compound B, compound A is converted into an enoltriflate, followed by a cross-coupling reaction using a boronating agent such as a tetra-alcoholate diboronic acid (bis(pinacolate) diboronic acid, for example) and a transition metal catalyst, to obtain a benzo[b]furan-3-boronic acid ester derivative. This compound is then subjected to a cross-coupling reaction using a sulfate derivative, such as various halogenated pyridine or hydroxy pyridine (xe2x80x9chalogenxe2x80x9d includes Cl, Br, or I, and xe2x80x9csulfatexe2x80x9d includes an ester of methanesulfonic acid, trifluoromethane sulfonic acid or the like, for example) and a transition metal catalyst to prepare compound B. The reaction is shown in the following reaction formula (2). 
Compound B can also be obtained by a condensation-cyclization reaction of a dihydroxybenzene derivative D, the hydroxyl group of which is protected by a protective group, with various bromoacetylpyridine derivatives E. The reaction is shown in the following reaction formula (3). 
Compound B is converted into compound C by a deprotecting reaction. Then, after converting compound C into a triflate, the objective compound (I) is prepared by a cross-coupling reaction using various types of aryl boronic acid, aryl boronic acid ester, or borane derivative. Furthermore, the objective compound (I) can also be obtained by modifying a substituent on the phenyl group or aromatic heterocyclic group shown as R, if necessary.
In the reactions shown by the above three chemical reaction formulae (1)-(3), the raw material compound and the intermediates may be either a free compound or a salt, similar to the compound (I). In addition, the reaction mixture may be subjected to the reaction either as is or after isolation according to a conventional method. Regarding the compounds or derivatives thereof provided for the reactions, the amino group, carboxyl group, and hydroxyl group not involved in the reactions may be protected using protective groups. Known methods, such as that described in xe2x80x9cPROTECTIVE GROUPS in ORGANIC SYNTHESISxe2x80x9d by T. W. Greene, P. G. M. Wuts, published by Wiley-Interscience (1999), and methods conforming to this method, may be applied to the addition and removal of the protective groups. As said protective group, an ether or ester of methyl, methoxymethyl, ethyl, 1-ethoxyethyl, phenacyl, tetra-hydropyranylbenzyl, and the like; a silyl ether or ester of trimethylsilyl, t-butyldimethylsilyl, and the like; an ester or amide of formic acid, acetic acid, and the like; and a carbonate or carbamate of benzyloxycarbonyl, t-butyloxycarbonyl, and the like can be used.
Usually, an organic solvent not affecting the reaction is used as a solvent. Examples of organic solvents not adversely affecting the reaction are: saturated hydrocarbons such as hexane, pentane and the like; amides such as N,N-dimethylformamide (DMF), N,N-dimethylacetamide and the like; halogenated hydrocarbons such as dichloromethane, chloroform and the like; ethers such as diethyl ether, dioxane, tetrahydrofuran (THF) and the like; esters such as methyl acetate, ethyl acetate and the like; alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 2-methyl-2- propanol, 1-butanol and the like; nitriles such as acetonitrile, propionitrile and the like; nitroalkanes such as nitromethane, nitroethane and the like; and aromatic hydrocarbons such as benzene, toluene, pyridine and the like. These solvents may be used either individually or in combination of two or more at an appropriate proportion.
When a base is used in the condensation reaction, triflatization reaction, and cross-coupling reaction, such base, for example, may include an alkali metal base such as lithium hydroxide, sodium hydroxide, potassium hydroxide, lithium carbonate, sodium carbonate, potassium carbonate, cesium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, trisodium phosphate, tripotassium phosphate, sodium acetate, and potassium acetate; an alkali metal hydride such as sodium hydride, potassium halide; an amine such as diisopropylethyl amine, 2,6-lutidine, 2,6-di-t-butylpyridine, 2,6-di-t-butyl-4-methylpyridine, and triethylamine; and the like.
When an acid is used in the cyclization reaction, such acid, for example, may include a mineral acid such as hydrochloric acid, hydrobromic acid, sulfuric acid, phosphoric acid, and polyphospholic acid; an organic acid such as trifluoroacetic acid, p-toluene sulfonic acid, and methanesulfonic acid; Lewis acid such as zinc chloride, tin chloride, boron trifluoride diethyl ether complex, aluminium chloride, and titanium tetrachloride; and the like.
Example transition metal catalysts used in the cross-coupling reaction (indicating homo or hetero nuclear bond-formation reaction represented as Heck reaction, Suzuki reaction, Ullmann reaction and the like, for example) are palladium, nickel, or copper, each having 0 to 2 valence. These metals may form a complex with triphenylphosphine, dibenzylidene acetone, bis-diphenyl phosphinoferrocene, and the like. The cross-coupling reaction is usually carried out at a temperature of xe2x88x9280 to 200xc2x0 C., and preferably 0 to 100xc2x0 C., for usually about 5 minutes to about 5 days, and preferably 30 minutes to 2 days.
The compounds and the salt thereof of the present invention can be orally or parenterally administered safely to human beings and animals as pharmaceuticals. Suitable means for parenteral administration are intravenous injection, intramuscular injection, hypodermic injection, intraperitoneal injection, percutaneous (transdermal) administration, transpulmonary administration, pernasal administration, transintestinal administration, intraoral administration, transmucosal administration, and the like. Preparations for these purposes are used. Specific examples of the preparations may include injection, suppositories, aerosol agents, percutaneous absorption tapes, and the like. Oral administration preparations include, for example, tablets (including sugar-coated tablets, coated tablets, buccal tablets), powder, capsules (including soft capsules), granules (including coated granules), pilules, troches, and liquid preparations, as well as their pharmaceutically acceptable sustained release preparations. Liquid preparations for oral administration include a suspension, emulsion, syrup, (including a dry syrup), and elixir.
These preparations are formulated according to known methods of making pharmaceutical preparations using pharmaceutically acceptable carriers, vehicles (excipients), disintegrators, lubricants, coloring agents, and the like for dosing as a pharmaceutical composition. Example carriers and vehicles used in these preparations are lactose, glucose, saccharose, mannitol, potato starch, cornstarch, calcium carbonate, calcium phosphate, calcium sulfate, crystalline cellulose, powdered glycyrrhiza, and powdered gentian. Example binders are starch, Tragacanth rubber, gelatin, syrup, polyvinyl alcohol, polyvinyl ether, polyvinyl pyrrolidone, hydroxypropyl cellulose, methylcellulose, ethyl cellulose, and carboxymethyl cellulose. Suitable disintegrator are starch, agar, gelatin powder, sodium carboxymethyl cellulose, calcium carboxymethyl cellulose, crystalline cellulose, calcium carbonate, sodium hydrogen carbonate, and sodium alginate. Example lubricants are magnesium stearate, talc, hydrogenated vegetable oils, macrogol, and the like. As coloring agents, any pharmaceutically acceptable coloring agents may be used.
Tablets and granules may be optionally coated with saccharose, gelatin, purified shellac, glycerol, sorbitol, ethyl cellulose, hydroxypropyl cellulose, hydroxypropylmethyl cellulose, polyvinyl pyrrolidone, phthalic acid cellulose acetate, hydroxypropylmethyl cellulose phthalate, methyl methacrylate, methacrylic acid polymer, and the like. These coating agents may be used either individually or in combination of two or more. Capsules made of a compound such as ethyl cellulose and gelatinxe2x80x94may also be used. When preparing a composition for injection, a pH adjusting agent, buffer agent, stabilizer, solubilizer, and the like, may optionally be added to the base component according to conventional methods.
When the compound of the present invention is administered to a patient, the dose varies depending on the conditions such as degree of symptom, age of the patient, health conditions, and body weight. A daily dose per adult for oral or non-oral administration may be in the range of 1-1000 mg, preferably 50-200 mg, and once or more per day, but not limited to this range.